Removable media such as a USB flash memory and SD card are generally used for carrying data between a plurality of computers. Using a removable medium, it is easy to read data stored in the removable medium into a computer and to write data stored in the computer in the removable medium.
On the other hand, since a security problem of, for example, sneaking confidential data out of a computer is posed, various methods of preventing data from being sneaked have been proposed.
For example, a technique which controls to permit use of only registered removable media has been proposed. With this technique, for example, an identifier (ID) of a removable medium, use of which is permitted in a computer, is pre-stored in the computer. When a removable medium is connected to the computer, it is determined whether use of the connected removable medium is permitted based on the stored ID of the removable medium. Then, data write accesses from the computer to the removable medium and read accesses of data stored in the removable medium can be controlled, thus suppressing sneaking data out of a computer.
However, an ID to be embedded in a removable medium such as a USB flash memory at the time of shipping of the removable medium depends on a vendor. Hence, no ID may be embedded in a removable medium or the same ID may be embedded in a plurality of removable media. It is difficult to control use of such removable media based on embedded IDs.